The seller even lists them as proofs. From my understanding, a replacement card would have a serial number filled in with marker to match the card it replaced. A card with no serial number would be a backdoor card. Both of these types of cards should be normal size.
I think if a card is an oversize cutout, it should be listed that way. If I were to want to purchase a replacement or backdoor card from you, I would expect a normal size card. This particular card was listed for $25 BIN OBO. I made an offer and then you did as well. Congrats on winning the card, it is cool. However, if it was a normal size card missing the serial number, I would have bought it for the $25 asking price with no hesitation.
For example, I purchased this card from you a while back:
http://juangone.com/pictures.php?cardid=96104
I didn't notice it prior to purchasing it, but you can tell from the picture of the back that it isn't cut straight. It is an oversize cutout but not listed as one. I am overall happy with our dealings in the past, but I didn't really get what I was expecting with that card.
That's my 2 cents. No hard feelings.